#include<stdio.h>
#include<assert.h>
char* css(char* a,const char * b)
{
	char* d=a;
	assert(a&&b);
	while(*a!='\0')
	{
		a++;
	}
	while(*a++ = *b++)
	{
		;
	}
	return d;
}
int main()
{
	char arr[20]="hello ";
	css(arr,"word");
	printf("%s\n",arr);
	printf("%s\n",css(arr,"word"));
	return 0;
}
